I. Field of the Invention
This invention relates generally to electrosurgical instruments, and more particularly to a bipolar electrosurgical coagulation instrument specifically designed for use in the performance of laparoscopic, endoscopic or similar procedures.
II. Discussion of the Prior Art
Heat has been used for the cauterization of bleeding wounds for centuries. Recently, the use of radio frequency (RF) energy traveling through the body has been widely used to stop bleeding. The RF energy cauterizes the blood vessels by heating proteins in the blood to a temperature where the proteins congeal. RF energy is preferred because its frequency is above that which could otherwise cause neuromuscular stimulation. At least two modes of RF cauterization are typically employed, namely monopolar or bipolar coagulation.
A monopolar electrosurgical system usually consists of an RF generator unit, an active electrode of small dimensions, and a large area return or dispersive electrode designed to be placed on the patients buttocks or thigh to serve as a return point for the RF energy released at the active electrode site. The active electrode is applied to the bleeding site and the current path is completed through the body to the return electrode which is electrically in contact with the patients skin surface.
Bipolar electrosurgical devices have the inherent advantage over monopolar devices of containing the RF energy. In a bipolar device, both the active and the return electrodes are placed on the surgical instrument. Thus, no separate return electrode on the patient is required as in monopolar systems. The RF energy remains at the site where the device is being used and only effects patient tissue in close proximity. Generally, bipolar devices are able to achieve the same results as competing monopolar devices while using a lower level of RF energy. Potential patient complications related to monopolar RF energy traveling through the body on a somewhat unpredictable path to the return electrode are avoided.
In the past, to cauterize blood vessels during a laparoscopic, endoscopic or similar procedure, either a cutting laser was used for small bleeding blood vessels, or a monopolar cauterization instrument was used for larger bleeders. These methods, however, have two significant drawbacks. Monopolar instruments, using RF energy, often have an unpredictable current flow path back to the return electrode. This unpredictable current flow may have a destructive effect on surrounding tissues. While non-contact positioning of a laser may overcome this problem, the laser has no way of holding a bleeding vessel and is not used on larger bleeders. The present invention overcomes both of these drawbacks by utilizing bipolar energy applied in an instrument that can effectively cauterize a bleeding blood vessel or vessels.
U.S. Pat. No. 4,005,714, entitled "Bipolar Coagulation Forceps," describes a forceps device which has two insulated current conductors terminating in a coaxial plug and a coaxial contact bushing. The conductors may be opened and closed by shifting an outer actuating sleeve with the aid of a handle that is stationary in relation to the forceps arms. The device moves the outer sleeve translationally in relation to the inner stationary sleeve and forceps device. In contrast, in the present invention an inner tube moves translationally within two concentric stationary outer tubes. The device of the '714 patent also differs from the present invention in that it has no means built into the handle for permitting rotation of the distal end of the instrument without turning the entire device. Conversely, the invention described herein incorporates the flexibility of a rotating distal end combined with a stationary handle to thereby better facilitate treatment of bleeding vessels. The present invention also allows introduction of a preset gap between opposing electrode surfaces to preclude shorting of the leads at the distal end and give better control over cauterization of bleeding tissue.
U.S. Pat. No. 3,920,021, describes devices for coagulating animal tissue by means of high frequency current. The device, as depicted, appears to show bipolar electrodes at the distal end of an outer tube. The proximal end of the outer tube and the proximal end of the inner tube are attached to a squeezable device that will move both the outer tube and the inner tube. Hence, neither the outer tube nor the inner tube is translationally stationary in relation to the handle. The device described in the '021 patent does not contain a means for rotating its distal end while holding the handle stationary or means for introducing a preset gap between the forceps' jaws.
Co-pending and commonly assigned U.S. patent application Ser. No. 08/013,852, filed Feb. 5, 1993, and entitled "Bipolar Electrosurgical Forceps," discloses a bipolar forceps device wherein both blades of the forceps move in relation to each other between an open and a closed configuration. This dual blade movement, while highly efficient, results in a device whose cross-sectional dimension may be too large for use in certain laparoscopic, endoscopic or similar procedures since the device is too large for travel within the lumen of such instrumentation.
The present invention is directed to a bipolar electrosurgical coagulation instrument which is specifically designed to be insertable through a canula for use in coagulating and cauterizing during laparoscopic, endoscopic or similar surgical procedures.
It is accordingly a primary object of the present invention to provide an electrosurgical instrument for carrying out laparoscopic, endoscopic or similar cauterization procedures.
Another object of the present invention is to provide an improved electrosurgical cauterization instrument for performing cauterization procedures requiring instrumentation travel through a scope canula of minimal cross-section dimension.
Yet another object of the present invention is to provide a bipolar electrosurgical instrument allowing better control over the location of cauterization treatment.
Yet another object of the present invention is to provide a bipolar electrosurgical cauterization instrument that has a rotatable distal end at the site of a procedure.
These and other objects of the present invention will become apparent throughout the following description.